Communication method, apparatus, and system

ABSTRACT

This application relates to the field of wireless communications, and in particular, to a communication method, an apparatus, and a system in a wireless communications system. In the method, a terminal device detects a physical downlink control channel PDCCH sent by a network device, the PDCCH carries indication information, and the indication information is used to indicate a type of system information; the terminal device determines, based on the indication information, a physical resource carrying the system information; and the terminal device receives the system information on the physical resource. Based on this method, a network device can flexibly indicate a type of system information that needs to be sent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2019/073353, filed on Jan. 28, 2019, which claims priority toChinese Patent Application No. 201810150873.9, filed on Feb. 13, 2018.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The application relates to the field of wireless communications, and inparticular, to a communication method, an apparatus, and a system in awireless communications system.

BACKGROUND

In a new radio (New Radio, NR) system, or in a 5th generation radioaccess (5G) system, a network device sends common information orspecific information to a terminal device through a physical downlinkshared channel (PDSCH), and instructs, by using downlink controlinformation (DCI) carried on a control channel, the terminal device todemodulate and receive the PDSCH. The common information includes systeminformation, and the system information is used to configure a frequencydomain reference point of an access bandwidth, a random access resource,and/or an uplink/downlink resource, and the like. The system informationmay include a plurality of types of information, for example, remainingminimum system information (Remaining minimum system information. RMSI)(or a system information type1 (system information block type1, SIB1))and other system information (Other system information, OSI). The systeminformation is applied to all terminal devices accessing correspondingcells.

On a premise that there are a plurality of types of system information,how to flexibly indicate a type of system information that needs to besent, to implement, by using fewer resource overheads, that the terminaldevice can correctly receive the system information of the type on aphysical resource carrying the system information is a technical problemthat urgently needs to be resolved.

SUMMARY

The application relates to a communication method, an apparatus, and asystem, to flexibly indicate a type of system information that needs tobe sent.

According to a first aspect, an embodiment of this application providesa communication method, and the method includes:

sending, by a network device, a physical downlink control channel PDCCHcarrying downlink control information, where the PDCCH carriesindication information, and the indication information is used toindicate a type of system information; determining, by the networkdevice, based on the type of the system information, a physical resourcecarrying the system information; and sending the system information byusing the physical resource; and

detecting, by a terminal device, a physical downlink control channelPDCCH carrying downlink control information, where the PDCCH carriesindication information, and the indication information is used toindicate a type of system information; determining, based on theindication information, a physical resource carrying the systeminformation; and receiving, by the terminal device, the systeminformation on the physical resource.

A cyclic redundancy code CRC included in the PDCCH is scrambled by aradio network temporary identifier RNTI.

In this manner, the type of the system information that needs to be sentcan be flexibly indicated, and by using fewer resource overheads, theterminal device can correctly receive the system information of the typeon the physical resource carrying the system information.

In an optional design, the indication information is a value of theRNTI.

The value of the RNTI is a first radio network temporary identifierRNTI, and the downlink control information is used to indicatefirst-type system information; and/or the value of the RNTI is a secondradio network temporary identifier RNTI, and the downlink controlinformation is used to indicate second-type system information.

In this method, different system information types may be determined byusing different values of the RNTI, and the type of the systeminformation that needs to be sent is flexibly indicated withoutincreasing resource and signaling overheads.

In an optional design, the indication information is format indicationinformation, and the format indication information is carried in thedownlink control information.

In this method, an existing field or information bit is reused toindicate the type of the system information, thereby improvingefficiency of indicating the type of the system information, andreducing complexity of a system design.

In an optional design, the network device sends a demodulation referencesignal DMRS of the physical resource carrying the system information.The terminal device obtains, based on a frequency domain referencepoint, the demodulation reference signal DMRS corresponding to thephysical resource carrying the system information. The frequency domainreference point corresponds to the type of the system information. Forexample, a first frequency domain reference point corresponds tofirst-type system information, and a second frequency domain referencepoint corresponds to second-type system information. The first frequencydomain reference point is different from the second frequency domainreference point, and the first-type system information is different fromthe second-type system information.

Specifically, a correspondence between the frequency domain referencepoint and the type of the system information is preconfigured orpredefined. Alternatively, the frequency domain reference point isindicated by using second indication information.

On a premise that the correspondence between the frequency domainreference point and the type of the system information is preconfiguredor predefined, the terminal device may obtain information about thefrequency domain reference point by using the indication information ofthe type of the system information, so that both the type of the systeminformation and the frequency domain reference point are obtainedwithout using additional indication information or fields, therebyimproving communication efficiency, and simplifying the system design.

In addition, a time domain resource and/or frequency domain resource ofthe PDCCH is indicated by using information carried in asynchronization/broadcast channel block.

According to a second aspect, an embodiment of the application providesa wireless apparatus, including a processor and a receiver, where

the processor is configured to detect a physical downlink controlchannel PDCCH carrying downlink control information, where the PDCCHcarries indication information, and the indication information is usedto indicate a type of system information;

the processor is configured to determine, based on the indicationinformation, a physical resource carrying the system information; and

the receiver is configured to receive the system information on thephysical resource.

A cyclic redundancy code CRC included in the PDCCH is scrambled with aradio network temporary identifier RNTI.

In an optional design, the indication information is a value of theRNTI.

The value of the RNTI is a first radio network temporary identifierRNTI, and the downlink control information is used to indicatefirst-type system information; and/or the value of the RNTI is a secondradio network temporary identifier RNTI, and the downlink controlinformation is used to indicate second-type system information.

In an optional design, the indication information is format indicationinformation, and the format indication information is carried in thedownlink control information.

Optionally, the processor is configured to obtain, based on a frequencydomain reference point, a demodulation reference signal DMRScorresponding to the physical resource carrying the system information;and the frequency domain reference point corresponds to the type of thesystem information.

Further, optionally, a correspondence between the frequency domainreference point and the type of the system information is preconfiguredor predefined. Alternatively, the frequency domain reference point isindicated by using second indication information.

A time domain resource and/or frequency domain resource of the PDCCH isindicated by using information carried in a synchronization/broadcastchannel block.

An embodiment of the application provides a network device, including atransmitter and a processor, where

the transmitter is configured to send a physical downlink controlchannel PDCCH carrying downlink control information, where the PDCCHcarries indication information, and the indication information is usedto indicate a type of system information; and

the processor is configured to determine, based on the type of thesystem information, a physical resource carrying the system information.

The PDCCH includes a cyclic redundancy code CRC, and the processor isconfigured to scramble the CRC by using a radio network temporaryidentifier RNTI.

In an optional design, the indication information is a value of theRNTI.

The value of the RNTI is a first radio network temporary identifierRNTI, and the downlink control information is used to indicatefirst-type system information; and/or the value of the RNTI is a secondradio network temporary identifier RNTI, and the downlink controlinformation is used to indicate second-type system information.

In an optional design, the indication information is format indicationinformation, and the format indication information is carried in thedownlink control information.

Optionally, the transmitter is configured to send a demodulationreference signal DMRS of the physical resource carrying the systeminformation. The DMRS corresponds to a frequency domain reference point,and the frequency domain reference point corresponds to the type of thesystem information.

Further, optionally, a correspondence between the frequency domainreference point and the type of the system information is preconfiguredor predefined. Alternatively, the transmitter is configured to sendsecond indication information, where the second indication informationis used to indicate the frequency domain reference point correspondingto the type of the system information.

A time domain resource and/or frequency domain resource of the PDCCH isindicated by using information carried in a synchronization/broadcastchannel block.

According to a third aspect, the application provides a system,including at least the two apparatuses according to the second aspect.

According to a fourth aspect, the application provides a wirelessapparatus, including one or more processors and a memory, where thememory stores a computer program, and when the processor executes thecomputer program, the apparatus is enabled to implement any methodaccording to the first aspect.

According to a fifth aspect, the application provides a computer storagemedium that stores a computer program, where the computer program isstored in the computer storage medium, and when the computer program isexecuted by a processor (or a device (a terminal device or a networkdevice)), any method according to the first aspect is implemented.

According to a sixth aspect, the application provides a computer programproduct that includes an instruction, and when the instruction is run ona computer, the computer is enabled to perform any method according tothe first aspect.

According to a seventh aspect, the application provides a chip system.The chip system includes a processor, configured to support a networkdevice or an apparatus in implementing a function in the first aspect,for example, generating or processing data and/or information in theforegoing method. In a possible design, the chip system further includesa memory. The memory is configured to store a program instruction anddata that are necessary for the network device or a communicationsapparatus. The chip system may include a chip, or may include a chip andanother discrete component.

According to an eighth aspect, the application provides a chip. The chipincludes a processing module and a communications interface. Theprocessing module is configured to control the communications interfaceto perform external communication. The processing module is furtherconfigured to implement any method according to the first aspect.

Compared with the prior art, in the solutions provided in embodiments ofthe application, the type of the system information that needs to besent can be flexibly indicated, and by using fewer resource overheads,the terminal device can correctly receive the system information of thetype on the physical resource carrying the system information.

BRIEF DESCRIPTION OF DRAWINGS

The following describes embodiments of the application in detail withreference to accompanying drawings.

FIG. 1 is a possible schematic diagram of an application scenarioaccording to an embodiment of the application:

FIG. 2 is a possible schematic structural diagram of a network deviceaccording to an embodiment of the application:

FIG. 3 is a possible schematic structural diagram of a terminal deviceaccording to an embodiment of the application;

FIG. 4 is a schematic diagram of a method of system message schedulingin time domain;

FIG. 5 is a schematic diagram of a location of a frequency domainreference point corresponding to a type of system information:

FIG. 6 is a possible schematic flowchart of a communication methodaccording to an embodiment of the application; and

FIG. 7 is a possible schematic structural diagram of a wirelessapparatus according to an embodiment of the application.

DESCRIPTION OF EMBODIMENTS

A network architecture and a service scenario described in theembodiments of the application are intended to describe the technicalsolutions in the embodiments of the application more clearly, and do notconstitute a limitation on the technical solutions provided in theembodiments of the application. A person of ordinary skill in the artcan learn that, with evolution of the network architecture and emergenceof a new service scenario, the technical solutions provided in theembodiments of the application are also applicable to similar technicalproblems.

In the embodiments of the application, “a plurality of” means two ormore than two. The term “and/or” describes an association relationshipbetween associated objects and represents that three relationships mayexist. For example, A and/or B may represent the following three cases:only A exists, both A and B exist, and only B exists. The character “/”generally indicates an “or” relationship between the associated objects.

FIG. 1 is a possible schematic diagram of an application scenarioaccording to an embodiment of the application. A communications systemin the application scenario includes a network device and one or moreterminal devices. The network device may communicate with the terminaldevices by using one or more air interface technologies.

The following describes terms that may appear in the embodiments of theapplication.

A communications system may be applicable to a long term evolution (LongTerm Evolution, LTE for short) system or another wireless communicationssystem that uses various radio access technologies, for example, asystem that uses access technologies such as code division multipleaccess, frequency division multiple access, time division multipleaccess, orthogonal frequency division multiple access, and singlecarrier frequency division multiple access. In addition, thecommunications system may also be applicable to an evolved LTE system,for example, a 5th generation 5G system.

A network device may be a base station, an access point, an accessnetwork device, or a device that is in an access network and thatcommunicates with a wireless terminal through one or more sectors on anair interface. The network device may be configured to mutually converta received over-the-air frame and an IP packet and serve as a routerbetween the wireless terminal and a remaining portion of the accessnetwork, where the remaining portion of the access network may includean Internet protocol (IP) network. The network device may furthercoordinate attribute management of the air interface. For example, thenetwork device may be a base transceiver station (Base TransceiverStation, BTS) in a global system for mobile communications (GlobalSystem for Mobile Communications, GSM) or code division multiple access(Code Division Multiple Access, CDMA), or may be a NodeB (NodeB, NB) inwideband code division multiple access (Wideband Code Division MultipleAccess, WCDMA), or may be an evolved NodeB (Evolutional Node B, eNB oreNodeB) in long term evolution (Long Term Evolution, LTE), a relay nodeor an access point, or a base station in a future 5G network, forexample, a gNB. This is not limited herein. It should be noted that, ina 5G or NR system, there may be one or more transmission receptionpoints (Transmission Reception Point, TRP) on one NR gNB. All TRPsbelong to a same cell, and each TRP and each terminal can use ameasurement reporting method described in this embodiment of theapplication. In another scenario, the network device may be furtherdivided into a control unit (Control Unit, CU) and a data unit (DataUnit, DU). One CU may correspond to a plurality of DUs. Each DU and eachterminal can use the measurement reporting method described in thisembodiment of the application. A difference between a CU-DU separationscenario and a multi-TRP scenario lies in that, the TRP is merely aradio frequency unit or an antenna device while the DU can implement aprotocol stack function, for example, the DU can implement a physicallayer function.

A terminal device may be a wireless terminal or a wired terminal. Thewireless terminal may be a device that provides a user with voice and/orother service data connectivity, a handheld device with a wirelessconnection function, or another processing device connected to awireless modem. The wireless terminal may communicate with one or morecore networks through a radio access network (Radio Access Network,RAN). The wireless terminal may be a mobile terminal, such as a mobilephone (also referred to as a “cellular” phone) and a computer with amobile terminal, for example, may be a portable, pocket-sized, handheld,computer built-in, or vehicle-mounted mobile apparatus, which exchangesvoice and/or data with the radio access network. For example, thewireless terminal may be a device such as a personal communicationservice (Personal Communication Service, PCS) phone, a cordlesstelephone, a session initiation protocol (Session Initiation Protocol,SIP) phone, a wireless local loop (Wireless Local Loop, WLL) station, ora personal digital assistant (Personal Digital Assistant, PDA). Thewireless terminal may also be referred to as a system, a subscriber unit(Subscriber Unit), a subscriber station (Subscriber Station), a mobilestation (Mobile Station), a mobile console (Mobile), a remote station(Remote Station), a remote terminal (Remote Terminal), an accessterminal (Access Terminal), a user terminal (User Terminal), a useragent (User Agent), or a user device (User Device or User Equipment).This not limited in the application.

A symbol includes but is not limited to an orthogonal frequency divisionmultiplexing (Orthogonal Frequency Division Multiplexing, OFDM) symbol,a sparse code multiple access (Sparse Code Multiplexing Access, SCMA)symbol, a filtered orthogonal frequency division multiplexing (FilteredOrthogonal Frequency Division Multiplexing, F-OFDM) symbol, and anon-orthogonal multiple access (Non-Orthogonal Multiple Access, NOMA)symbol. The symbol may be specifically determined based on an actualcase. Details are not described herein.

A control resource set (Control Resource Set, CORESET) is a resource setused for control channel transmission. Time domain resources in aCORESET may be consecutive or inconsecutive.

A subframe occupies a time-frequency resource of entire system bandwidthin frequency domain, and occupies a fixed time length in time domain,for example, one millisecond (ms). In addition, one subframe may alsooccupy K consecutive symbols, where K is a natural number greater than0. A value of K may be determined based on an actual case, and this isnot limited herein. For example, in LTE, one subframe occupies 14consecutive OFDM symbols in time domain.

A slot is a basic time-frequency resource unit, and occupies Lconsecutive OFDM symbols in time domain, where L is a natural numbergreater than 0. A value of L may be determined based on an actual case.For example, there may be seven OFDM symbols.

A physical resource block (Physical Resource Block, PRB) is a frequencydomain resource unit and occupies M contiguous subcarriers in frequencydomain, where M is a natural number greater than 0. For example, M isequal to 12 or 16.

A bandwidth part (Bandwidth part, BWP) is a plurality of contiguousphysical resource blocks in frequency domain, and the physical resourceblocks are generally configured by a network device for a terminaldevice. The terminal device receives or sends data in the BWP. In anexample of control resource transmission, one BWP includes at least onecontrol resource set, and frequency domain resources included in thecontrol resource set do not exceed a plurality of physical resourceblocks included in the BWP in frequency domain. The BWP is classifiedinto an initial active bandwidth part (Initial active BWP) and aUE-specific bandwidth part (UE-specific BWP). The initial active BWP isconfigured by using broadcast information, for example, a masterinformation block (master information block. MIB), and the UE-specificBWP is configured by using UE-specific radio resource control (radioresource control, RRC) signaling.

Initial active bandwidth part (Initial active BWP): Before entering aconnected mode or obtaining terminal device-specific BWP configurationinformation, a terminal device needs to receive or send data on theinitial active BWP. Specifically, a frequency domain location and abandwidth size of the initial active BWP are configured by usingbroadcast information. In addition, the bandwidth size is equal to afrequency domain range occupied by a control resource set CORESETconfigured by using the broadcast information.

A common index scheme (Common Index Scheme) is an index schemestipulated in a standard or a protocol, determined by a network devicein a communications system, or determined by a plurality of networkdevices in a communications system through negotiation. The index schemeis used for resource configuration. In the communications system, acontrol resource and/or a data resource configured by a network devicefor a terminal device served by the network device are/is located in acommon index area determined based on the common index scheme.

A common index area is a plurality of contiguous physical resourceblocks in frequency domain that are obtained based on a common indexscheme (common index scheme). A bandwidth part BWP is located in thecommon index area.

A demodulation reference signal, DMRS (Demodulation reference signal)for short, is used for demodulating a received physical channel.Specifically, a DMRS carried on the physical channel is a DMRS signalgenerated by mapping a DMRS sequence to a physical resource. Forexample, a downlink DMRS may be used to demodulate a physical downlinkshared channel PDSCH.

System information, SI (System information) for short, is used toconfigure a frequency domain reference point of an access bandwidth, andused for a resource for random access and/or an uplink/downlinkresource, and the like. The system information includes a plurality oftypes of system information, for example, RMSI or a SIB1, and othersystem information OSI (Other system information), for example, a SIB2.The OSI herein may include all types of system information except theRMSI.

Further, a possible schematic structural diagram of the foregoingnetwork device may be shown in FIG. 2. A network device can perform themethod provided in the embodiments of the application. The networkdevice may include a controller or processor 201 (the following uses theprocessor 201 as an example for description) and a transceiver 202. Thecontroller/processor 201 sometimes may also be referred to as a modemprocessor (modem processor). The modem processor 201 may include abaseband processor (baseband processor, BBP) (not shown). The basebandprocessor processes a received digitalized signal, to extractinformation or a data bit transmitted in the signal. Therefore, based ona requirement or an expectation, the BBP is usually implemented in oneor more digital signal processors (digital signal processor. DSP) in themodem processor 201 or implemented as a separated integrated circuit(integrated circuit, IC).

The transceiver 202 may be configured to support sending and receivinginformation between a network device and a terminal device, and supportradio communication between terminal devices. The processor 201 may befurther configured to perform various functions for communicationbetween the terminal device and the network device. In uplink, an uplinksignal from the terminal device is received by using an antenna,demodulated by the transceiver 202, and further processed by theprocessor 201, to restore service data and/or signaling information sentby the terminal device. In downlink, service data and/or a signalingmessage are/is processed by the terminal device, modulated by thetransceiver 202 to generate a downlink signal, and transmitted by theantenna to the terminal device. The network device may further include amemory 203, and the memory 203 may be configured to store program codeand/or data of the network device. The transceiver 202 may include anindependent receiver and transmitter circuit, or may implement receivingand sending functions in one circuit. The network device may furtherinclude a communications unit 204, and the communications unit 204 isconfigured to support communication between the network device andanother network entity. For example, the network device is configured tosupport communication between the network device and a network device ofa core network, and the like.

Optionally, the network device may further include a bus. Thetransceiver 202, the memory 203, and the communications unit 204 may beconnected to the processor 201 by using the bus. For example, the busmay be a peripheral component interconnect (Peripheral ComponentInterconnect, PCI) bus, an extended industry standard architecture(Extended Industry Standard Architecture, EISA) bus, or the like. Thebus may include an address bus, a data bus, a control bus, and the like.

FIG. 3 is a possible schematic structural diagram of the terminal devicein the foregoing communications system. The terminal device can performthe method provided in the embodiments of the application. The terminaldevice may be any one of one or more terminal devices in FIG. 1. Theterminal device includes a transceiver 301, an application processor(application processor) 302, a memory 303, and a modem processor (modemprocessor) 304.

The transceiver 301 may adjust (for example, perform analog conversion,filtering, amplification, and up-conversion on) an output sample andgenerate an uplink signal. The uplink signal is transmitted to the basestation in the foregoing embodiment by using an antenna. In downlink,the antenna receives a downlink signal transmitted by a network device.The transceiver 301 may adjust (for example, perform filtering,amplification, down-conversion, and digitalization on) a signal receivedfrom the antenna and provide an input sample.

The modem processor 304 is sometimes referred to as a controller orprocessor, and may include a baseband processor (baseband processor,BBP) (not shown). The baseband processor processes a receiveddigitalized signal, to extract information or a data bit transmitted inthe signal. Based on a requirement or an expectation, the BBP is usuallyimplemented in one or more digital signal processors in the modemprocessor 304 or implemented as a separated integrated circuit (IC).

In a design, the modem processor (modem processor) 304 may include anencoder 3041, a modulator 3042, a decoder 3043, and a demodulator 3044.The encoder 3041 is configured to encode a to-be-sent signal. Forexample, the encoder 3041 may be configured to receive service dataand/or a signaling message that are/is to be sent in uplink, and performprocessing (for example, formatting, encoding, or interleaving) on theservice data and the signaling message. The modulator 3042 is configuredto modulate an output signal of the encoder 3041. For example, themodulator may perform processing such as symbol mapping and/ormodulation on the output signal (data and/or signaling) of the encoder,and provide an output sample. The demodulator 3044 is configured todemodulate an input signal. For example, the demodulator 3044 processesan input sample and provides symbol estimation. The decoder 3043 isconfigured to decode a demodulated input signal. For example, thedecoder 3043 performs processing such as de-interleaving and/or decodingon the demodulated input signal, and outputs a decoded signal (dataand/or signaling). The encoder 3041, the modulator 3042, the demodulator3044, and the decoder 3043 may be implemented by the integrated modemprocessor 304. These units perform processing based on a radio accesstechnology used in a radio access network.

The modem processor 304 receives, from the application processor 302,digitalized data that may represent voice, data, or control information,and processes the digitalized data for transmission. The modem processormay support one or more of a plurality of wireless communicationprotocols of a plurality of communications systems, for example, LTE,new radio, a universal mobile telecommunications system (UniversalMobile Telecommunications System, UMTS), and high speed packet access(High Speed Packet Access, HSPA). Optionally, the modem processor 304may also include one or more memories.

Optionally, the modem processor 304 and the application processor 302may be integrated in one processor chip.

The memory 303 is configured to store program code (sometimes alsoreferred to as a program, an instruction, software, or the like) and/ordata that are/is used to support communication of the terminal device.

It should be noted that the memory 203 or the memory 303 may include oneor more storage units, for example, may be a storage unit that is in theprocessor 201, the modem processor 304, or the application processor 302and that is configured to store program code, or may be an externalstorage unit independent of the processor 201, the modem processor 304,or the application processor 302, or may be further a componentincluding a storage unit inside the processor 201, the modem processor304, or the application processor 302 and an external storage unitindependent of the processor 201, the modem processor 304, or theapplication processor 302.

The processor 201 and the modem processor 304 (the processor 304 forshort hereinafter) may be processors of a same type or processors ofdifferent types. For example, the processor 201 and modem processor 304may be implemented as a central processing unit (Central ProcessingUnit, CPU), a general-purpose processor, a digital signal processor(Digital Signal Processor, DSP), an application-specific integratedcircuit (Application-Specific Integrated Circuit, ASIC), a fieldprogrammable gate array (Field Programmable Gate Array, FPGA), oranother programmable logic device, a transistor logic device, a hardwarecomponent, another integrated circuit, or any combination thereof. Theprocessor 201 and the modem processor 304 may implement or executevarious example logical blocks, modules, and circuits described withreference to content disclosed in the embodiments of the application.The processor may also be a combination that implements a computingfunction device, for example, a combination including one or moremicroprocessors, a combination of a DSP and a microprocessor, or asystem-on-a-chip (system-on-a-chip, SOC).

A person skilled in the art can understand that various explanatorylogic blocks, modules, circuits, and algorithms described with referenceto the various aspects disclosed in this application may be implementedas electronic hardware, an instruction that is stored in a memory oranother computer readable medium and that is executed by a processor oranother processing device, or a combination thereof. As an example, thedevice described in this specification may be applied to any circuit,hardware component, IC, or IC chip. The memory disclosed in thisapplication may be any type of memory in any size, and may be configuredto store any type of required information. To clearly explain suchinterchangeability, various explanatory components, blocks, modules,circuits, and steps have been generally described above based onfunctionality. How to implement such functionality depends on a specificapplication, a design selection, and/or a design constraint that isimposed on an entire system. A person skilled in the art may usedifferent manners to implement the described functions for eachparticular application, but it should not be considered that suchimplementation goes beyond the scope of the application.

In the embodiments of the application, sending a downlink (uplink)channel may be sending data or information carried on the downlink(uplink) channel. The data or information may be data or informationobtained after channel coding.

It should be noted that, a term “start resource block” is used in theembodiments of the application. The term may refer to a resource blockhaving a minimum subcarrier sequence number in resource blocks includedin a specific area (for example, a common index area or a bandwidthpart), or a resource block having a minimum sequence number whenincluded resource blocks are numbered from a low frequency to a highfrequency; or may refer to a resource block having a maximum subcarriersequence number in resource blocks included in a specific area (forexample, a common index area or a bandwidth part), or a resource blockhaving a maximum sequence number when included resource blocks arenumbered from a low frequency to a high frequency. The low frequency andthe high frequency are defined in relative to a subcarrier sequencenumber, and a subcarrier sequence number of a low frequency location isless than a subcarrier sequence number of a high frequency location. Nospecific limitation is imposed in the embodiments. A specific meaning ofthe start resource block depends on a requirement of an actualcommunications system, a notification from the network device, or astipulation in a standard or a protocol. In the embodiments of theapplication, an example in which the start resource block is theresource block having the minimum subcarrier number in the resourceblocks included in the specific area (for example, the common index areaor the bandwidth part), or the resource block having the minimumsequence number when the included resource blocks are numbered from thelow frequency to the high frequency is used for description.

A person skilled in the art may know that there are a plurality of typesof system information, and a physical downlink shared channel (physicaldownlink shared channel, PDSCH) carrying RMSI or OSI is used as anexample in this specification. However, the embodiments of theapplication are not limited thereto, and all types of system informationand physical channels or physical resources that may be used in theembodiments of the application shall fall within the protection scope ofthe application.

A person skilled in the art may know that the PDSCH is scheduled byusing downlink control information. The terminal device needs to detectdownlink control information (downlink control information, DCI) carriedon a physical downlink control channel (physical downlink controlchannel, PDCCH), to further obtain system information carried on thePDSCH to access a serving cell or a carrier. For details, refer to FIG.4.

Because a system bandwidth on a network device side in an NR system isgreater than a bandwidth actually accessed by the terminal device, aconfiguration of a frequency domain reference point is introduced. Agranularity of the frequency domain reference point may be a resourceblock, or may be a subcarrier in a resource block, for example, asubcarrier having a minimum number or a subcarrier numbered 0 in theresource block. In this embodiment of the application, an example inwhich the granularity of the frequency domain reference point is theresource block is used for description, but the protection scope is notlimited thereto.

The configuration of the frequency domain reference point in thisembodiment of the application may have the following various optionaldesigns.

In an optional design, the frequency domain reference point isirrelevant to a type of system information, and frequency domainreference points corresponding to different types of system informationare the same or different.

In another optional design, the frequency domain reference point isrelated to the type of the system information, and different types ofsystem information correspond to different frequency domain referencepoints. For example, RMSI is first-type system information, OSI issecond-type system information, and the RMSI and the OSI correspond todifferent frequency domain reference points. Specifically, frequencydomain positions of the PDSCH carrying the RMSI or OSI are different dueto the different frequency domain reference points, and/or DMRSs used todemodulate the PDSCH are different due to the different frequency domainreference points.

Optionally, a frequency domain reference point on the network deviceside is configured by using the system information RMSI, so that beforethe terminal device obtains the RMSI, the frequency domain referencepoint is configured as a start resource block of an initial active BWP(or in a control channel resource set configured by a broadcast channel)or a subcarrier numbered 0 in a start resource block of an initialactive BWP, and the frequency domain reference point may be denoted as afrequency domain reference point A. After receiving the RMSI, theterminal device can determine a common frequency domain reference pointin a broadband carrier configured by a network device, where the commonfrequency domain reference point is a start resource block of a commonindex area or a subcarrier numbered 0 in a start resource block of acommon index area, and the common frequency domain reference point maybe denoted as a frequency domain reference point B. Further, thefrequency domain reference point affects determining of the frequencydomain location of the PDSCH carrying the RMSI or OSI and/or the DMRS ofthe PDSCH carrying the RMSI or OSI.

Specifically, before demodulating the PDSCH, the terminal device needsto obtain a DMRS sequence, where the DMRS sequence is generated byintercepting a part of a sequence from a reference DMRS sequence. Theterminal device matches a received DMRS signal based on a locallygenerated or obtained DMRS sequence, and demodulates and/or decodes thePDSCH. Further, if different types of system information correspond to asame frequency domain reference point and a same DMRS, the terminaldevice may correctly demodulate the PDSCH. If different frequency domainreference points correspond to different system information types, DMRSsequences that are obtained from the reference DMRS sequence and thatcorrespond to different information types are also different. If theDMRS sequences obtained by the terminal device do not match a DMRSsignal sent by the network device, the terminal device cannot correctlydemodulate and receive the PDSCH. The reference DMRS sequence is a Goldsequence generated based on configuration information or a predefinedparameter. For example, the terminal device generates the Gold sequencebased on obtained identity information or a cell identity (ID). The Goldsequence is a pseudo-random sequence proposed on a basis of anm-sequence. For details, refer to the prior art. The reference DMRSsequence includes a plurality of values, and each value may be a complexvalue. For DMRS demodulation, refer to description in the prior art ordemodulation performed by using the prior art.

For example, a resource occupied by the DMRS in each RB in a given OFDMsymbol is two REs, and if a system information type corresponds to afrequency domain reference point A, a mapped DMRS sequence in the n^(th)RB in the initial active BWP is the 2n^(th) value and the (2n+1)^(th)value in the reference DMRS sequence. If the system information typecorresponds to a frequency domain reference point B, and an RB number ofthe start resource block of the initial active BWP in the common indexarea is no, the mapped DMRS sequence in the n^(th) RB in the initialactive BWP is the 2(n₀+n)^(th) value and the (2(n₀+n)+1)^(th) value inthe reference DMRS sequence.

In addition, the terminal device obtains a PDSCH frequency domainresource based on the frequency domain reference point. If the frequencydomain reference points are different, PDSCH frequency domain resourcelocations obtained by the terminal device are also different. Forexample, one bit in PDSCH frequency domain resource indicationinformation that is included in the DCI corresponds to one RB group (RBGroup, RBG) in frequency domain, and RBs included in the RB group are aplurality of contiguous RBs in frequency domain. The RB group isgenerated by grouping RBs from a low frequency to a high frequency andstarting from the frequency domain reference point. RBs in different RBgroups do not overlap, and a quantity of RBs included in the pluralityof RB groups is in a decreasing trend from a low frequency to a highfrequency. Optionally, the plurality of RB groups may further include atleast two RB groups that are adjacent in frequency domain and that havea same quantity of RBs, and the quantity is in an overall decreasingtrend. For example, a quantity of RBs in the RB group at a highfrequency location is not greater than a quantity of RBs in the RB groupat a frequency domain location lower than the high frequency location.Further, an RB group starting from the frequency domain reference pointA and an RB group starting from the frequency domain reference point Bare RB groups classified based on different frequency domain referencepoints. Even if the PDSCH frequency domain resource indicationinformation indicated by using the DCI are the same, the PDSCH frequencydomain locations are also different.

An example in which the system information type is RMSI or OSI is used,as shown in FIG. 5, a reference point of a PDSCH frequency domainlocation carrying the RMSI is a reference point A, and a reference pointof a PDSCH frequency domain location carrying the OSI is a referencepoint B. The terminal device obtains PDSCH resource indicationinformation. When the frequency domain reference point A is differentfrom the frequency domain reference point B, PDSCH frequency domainlocations indicated by the PDSCH resource indication information arealso different corresponding to different frequency domain referencepoint A or B.

It can be learned from the foregoing that if different systeminformation types and/or frequency domain reference points correspondingto the system information types cannot be distinguished, systeminformation fails to be received, and consequently, the terminal devicecannot access a serving cell or a carrier.

In an optional solution, a type of the system information may beassociated with a time domain location, and the association relationshipmay be predefined or preconfigured, for example, predefined in astandard or a protocol. Specifically, for example, a time domainlocation of downlink control information used to indicate the RMSI (ormay also be referred to as a time domain location corresponding to theRMSI) is predefined or preconfigured as, for example, the first slot andthe eleventh slot in every 20 slots (Slot).

The network device sends, on a predefined first time domain resource,the downlink control information used to indicate the RMSI, and the RMSIcorresponds to the frequency domain reference point A in FIG. 5. Itshould be noted herein that, if the downlink control information used toindicate a system information type except the RMSI overlaps the timedomain resource, the network device preferentially sends the downlinkcontrol information used to indicate the RMSI, to ensure that theterminal device can detect, on the predefined time domain resource, thedownlink control information used to indicate the RMSI. In this case,the terminal device detects, only in a predefined time domain resourcearea (also referred to as monitor window (monitor window) herein), thedownlink control information used to indicate that the systeminformation is the RMSI, the terminal device may determine, based on thefrequency domain reference point A, B, or another possible frequencydomain reference point, a frequency domain location of a PDSCH carryingthe RMSI and a corresponding DMRS sequence. [00%] If downlink controlinformation used to indicate system information is detected in a secondtime domain resource area (namely, outside the monitor window), theterminal device determines, based on the frequency domain referencepoint A. B, or another possible frequency domain reference point, afrequency domain location of a PDSCH carrying other system informationOSI that is different from the RMSI and a DMRS sequence.

The terminal device detects RNTI information scrambled with a CRC in aPDCCH carrying the downlink control information, and the RNTIinformation is used to determine that the detected downlink controlinformation is used to instruct to receive the system information. Forexample, if the RNTI information is an SI-RNTI, the detected downlinkcontrol information is used to instruct to receive the systeminformation. For scrambling and descrambling of the RNTI, refer todescription in the prior art, or the scrambling and descrambling may beimplemented in a manner in the prior art. This is not specificallylimited herein.

In the foregoing solution, a time domain resource on which the downlinkcontrol information is used to indicate the reception of the systeminformation is associated with type of the system information, andresource scheduling is also limited when the type of the systeminformation is implicitly indicated. As a result, resource overheads ofthe network device increase and scheduling is not flexible enough. Inaddition, the terminal device cannot accurately obtain frequency domainreference point information. As a result, the terminal device cannotcorrectly demodulate and/or decode a physical resource carrying thedownlink control information.

To resolve the foregoing technical problem, an embodiment of theapplication further provides a communication method, to implementflexible indication of a system information type with fewer resourceoverheads.

The following further describes this embodiment of the application indetail based on a common aspect of the application described above.Possible uplink and downlink latencies are ignored in descriptions ofthis embodiment. It is assumed that a sending moment of a network deviceis the same as a receiving moment of a terminal device. For processingcorresponding to sending operation of the network device and receivingoperation of the terminal device, this embodiment is described mainlyfrom a perspective of a terminal device side. A person skilled in theart may understand that, the receiving of the terminal device from thenetwork device means that the network device performs sending.

In addition, sequence numbers of steps in this embodiment of theapplication do not limit a sequence of a specific execution process. Anexecution sequence of the steps is adaptively adjusted in differentoptional designs.

Embodiment 1

An embodiment of the application provides a communication method. In themethod, a network device sends a physical downlink control channelPDCCH, a terminal device detects a physical downlink control channelPDCCH carrying downlink control information, the PDCCH carriesindication information, where the indication information is used toindicate a type of system information, and the terminal devicedetermines, based on the indication information, a physical resourcecarrying the system information. According to the method provided inEmbodiment 1 of the application, a type of the system information can beflexibly indicated without increasing resource overheads.

FIG. 6 shows a specific implementation of the communication method inEmbodiment 1 of the application. The following describes a solutionprovided in Embodiment 1 of the application with reference to FIG. 6.

Step 600: A network device determines to send system information, andthe system information is first-type system information or second-typesystem information.

Optionally, the first-type system information is RMSI or a systeminformation block type1 (SystemInformationBlockType1, SIB1), and/or thesecond-type system information is OSI or a system information SImessage.

Before step 600, the network device determines, based on a status of acurrent communications system and/or a further scheduling requirement,that specific-type system information, for example, the RMSI, the SIB1,or an SIB2, needs to be sent. Details are not described herein, and aspecific manner may be the same as that in the prior art.

The determining step may be performed by a processor of the networkdevice.

Step 601: The network device sends a physical downlink control channelPDCCH carrying downlink control information, the PDCCH carriesindication information, and the indication information is used toindicate a type of system information.

The sending step may be performed by a transmitter of the networkdevice.

Before step 601, the method further includes the following step: Thenetwork device indicates a time domain resource and/or frequency domainresource of the PDCCH by using information carried in asynchronization/broadcast channel block.

Specifically, a master information block MIB carried on a broadcastchannel in the synchronization/broadcast channel block (synchronoussignal/physical broadcast channel block, SS/PBCH block) includesconfiguration information of the time domain resource and/or frequencydomain resource of the PDCCH. Specifically, N high-order bits in anRMSI-PDCCH-Config field in the MIB are used to configure a quantity of aplurality of contiguous resource blocks in frequency domain and aquantity of a plurality of consecutive OFDM symbols in time domain, andM low-order bits in the RMSI-PDCCH-Config field are used to configure amonitoring occasion (monitoring occasion) of the PDCCH, where both M andN are positive integers. Optionally, M=N=4. Further, four bits mayindicate 16 bit values or bit states, and a correspondence existsbetween different bit values or bit states and resource configurations.The correspondence may be preconfigured or predefined, for example,predefined in a table of a standard or protocol.

Step 602: The network device determines, based on the type of the systeminformation, a physical resource carrying the system information.

The physical resource may be a time domain resource and/or frequencydomain resource of a physical downlink shared channel PDSCH.

The frequency domain resource may be determined by the network device ina plurality of manners, for example, may be determined in a same orsimilar manner as that of a terminal device. For details, refer to theforegoing description.

Optionally, the network device obtains a DMRS sequence based on afrequency domain reference point or the type of the system information,and the DMRS sequence is a part of a reference DMRS sequence, forexample, may be generated by intercepting a part of sequence from areference DMRS sequence. Further, the network device determines thefrequency domain location of the PDSCH. The network device modulates theDMRS sequence onto the physical resource, and sends the PDSCH carryingthe system information.

Specifically, based on the foregoing description, DCI carried on thePDCCH includes PDSCH frequency domain resource indication information,and the PDSCH frequency domain resource indication information is usedto notify the terminal device of a frequency domain resource of thePDSCH. A length of a bit sequence included in the PDSCH frequency domainresource indication information is related to a frequency domain size ofa BWP on which the PDSCH scheduled by using the DCI is located, and eachbit indicates one RBG Alternatively, values or bit states of a group ofbits correspond to a plurality of contiguous RBs on a frequency domainresource. The PDSCH frequency domain resource indication information mayinclude one or more bits, each bit corresponds to one RB group (RBGroup, RBG) in frequency domain, and RBs included in the RB group are aplurality of contiguous RBs in frequency domain. For the terminaldevice, the frequency domain resource of the PDSCH is determined byusing the frequency domain reference point and the PDSCH frequencydomain resource indication information included in the DCI.

The network device may determine the time domain resource in a pluralityof manners.

Optionally, the time domain resource may be predefined or preconfigured,and is notified to the terminal device in advance.

Optionally, the time domain resource is dynamically or semi-staticallyconfigured by the network device, and is notified to the terminal deviceby using the DCI. Further, optionally, the network device may directlyindicate the time domain resource by using the DCI, or instruct, byusing the DCI, the terminal device to determine the time domainresource. For example, an index of the time domain resource is indicatedby using the DCI, and the index is used to indicate the time domainresource, so that the terminal device determines a location of the timedomain resource by using the index.

The determining step may be performed by the processor 201 of thenetwork device.

Step 603: The terminal device detects the physical downlink controlchannel PDCCH carrying the downlink control information, and the PDCCHcarries the indication information.

Before step 601, a cyclic redundancy code (cyclic redundancy code, CRC)included in the PDCCH is scrambled by a radio network temporaryidentifier RNTI, and the scrambled CRC is used by the terminal device todetect whether a received PDCCH is correct and a scheduling type of thePDCCH.

The detection step may be performed by a processor of the terminaldevice, or may be performed by a transceiver controlled by a processorof the terminal device.

The detection in step 603 is blind detection. Specifically, the networkdevice scrambles the CRC included in the PDCCH in step 601, and thescrambling is performed on 16 low-order bits of the CRC based on a valueof the RNTI. The terminal device performs blind detection based on theRNTI, and determines, based on that the RNTI of the DCI that issuccessfully detected is an SI-RNTI, that information needed to bereceived is the system information. The RNTI further includes a C-RNTI,an RA-RNTI, and the like. For a specific type of the RNTI, refer to theprior art. Details are not described herein.

Optionally, the indication information may be a value of the RNTI usedfor scrambling, or may be information carried in the DCI, for example,one or more bits. For details, refer to description in the followingembodiments.

Step 604: The terminal device determines, based on the indicationinformation, a physical resource carrying the system information.

The physical resource may be a time domain resource and/or frequencydomain resource of a physical downlink shared channel PDSCH.

For a determining manner of the frequency domain resource, refer to theforegoing description.

Specifically, the terminal device may obtain, based on a frequencydomain reference point and PDSCH frequency domain resource indicationinformation included in the DCI, the frequency domain resource of thePDSCH. The PDSCH frequency domain resource indication information isused to indicate one or more RB groups corresponding to the PDSCH.Before demodulating the PDSCH, the terminal device needs to obtain aDMRS sequence, for example, determine the DMRS sequence based on thefrequency domain reference point. The DMRS sequence is a part of areference DMRS sequence. For example, the DMRS sequence may be generatedby intercepting the part of the sequence from the reference DMRSsequence. The terminal device matches a received DMRS signal based on alocally generated or obtained DMRS sequence, and demodulates and/ordecodes the PDSCH.

The terminal device may determine the time domain resource in one of aplurality of optional manners.

Optionally, the time domain resource may be predefined or preconfigured,and is notified to the terminal device in advance.

Optionally, the time domain resource is dynamically or semi-staticallyconfigured by the network device, and is notified to the terminal deviceby using the DCI. Further, optionally, the terminal device may directlydetermine the time domain resource by using information carried in theDCI, or the terminal device further determines, by using the informationcarried in the DCI, the time domain resource. For example, what the DCInotifies is an index of the time domain resource, and the terminaldevice further determines the time domain resource by using the index.Optionally, a correspondence between the index and the time domainresource is predefined or preconfigured, for example, predefined in astandard or a protocol. The correspondence may be shown in Table 1.

TABLE 1 Index (index) Time interval K0 Indication information RIV 0 0 21 0 4 2 1 8 3 1 10

The index column lists indexes corresponding to a time domain resourcelocation notified by the DCI. Optionally, the index may be carried by atime domain resource assignment (Time domain resource assignment) fieldin the DCI. For example, the field includes two bits, where {00}corresponds to an index0, {01} corresponds to an index1, {10}corresponds to an index2, and {11} corresponds to an index3. The timeinterval KO is a time interval between a detected PDCCH and a PDSCHscheduled by the PDCCH, and is expressed in slots. The indicationinformation RIV is indication information of a time domain startlocation and a length of the PDSCH within a slot. Each RIV valuecorresponds to a time domain location of a PDSCH within a slot.

The terminal device determines, based on the correspondence between theindex and the time domain resource location, the time domain resource ofthe PDSCH.

The determining step may be performed by the processor 304 of theterminal device.

Step 605: The terminal device receives the system information on thephysical resource carrying the system information.

The receiving step may be performed by the transceiver of the terminaldevice, or may be performed by the transceiver controlled by theprocessor of the terminal device.

According to the communication method implemented in steps 600 to 605,the type of the system information can be flexibly indicated withoutincreasing the resource overheads, thereby improving communicationefficiency.

In step 601, the network device sends the PDCCH carrying the downlinkcontrol information, and in step 603, the terminal device detects thePDCCH carrying the downlink control information, and the PDCCH carriesthe indication information, where the indication information is used toindicate the type of the system information. The PDCCH sent by thenetwork device includes the CRC, and the CRC or the 16 low-order bits ofthe CRC are scrambled by the RNTI. The terminal device detects the PDCCHby using the RNTI. In the foregoing two steps, for a specific CRCalgorithm, refer to the prior art. Details are not described herein.There may be a plurality of optional designs for the indicationinformation that is used to indicate the type of the system informationand that is in the foregoing two steps, and details are described in thefollowing.

In an optional design, the indication information is a value of theRNTI, where the value of the RNTI is a first radio network temporaryidentifier RNTI, and the downlink control information is used toindicate first-type system information; and/or the value of the RNTI isa second radio network temporary identifier RNTI, and the downlinkcontrol information is used to indicate second-type system information.A correspondence between the value of the RNTI and the type of thesystem information may be predefined or preconfigured, for example,predefined by using a protocol or a standard, or is notified orconfigured by the network device to the terminal device in advance, anda specific notification or configuration time may be known by theterminal device when the terminal device performs PDCCH descrambling anddecoding.

Specifically, the SI-RNTI used to indicate the system information mayinclude an SI-RNTI0 and an SI-RNTI1. For example, a value of theSI-RNTI0 is FFFF, and/or a value of the SI-RNTI1 is another value thatis not equal to FFFF, for example, FFF0. It should be noted herein thata specific RNTI value used to distinguish different system informationtypes may be another value or in another form. This is not specificallylimited herein.

In step 602, the network device determines, based on the type of thesystem information, the physical resource carrying the systeminformation, and in step 604, the terminal device determines, based onthe indication information, the physical resource carrying the systeminformation. Herein, the network device and the terminal device maydetermine the physical resource by using a same or similar principle.

In step 603, the terminal device detects the physical downlink controlchannel PDCCH carrying the downlink control information. If descramblingsucceeds by using the SI-RNTI0, for example, FFFF, the DC instructs theterminal device to receive the first-type system information. Ifdescrambling succeeds by using the SI-RNTI1, for example, another valueother than FFFF, the DCI instructs the terminal device to receive thesecond-type system information.

In another optional design, the indication information is formatindication information (Identifier for DCI formats), and the formatindication information is carried in the downlink control information.In this optional design, the CRC of the PDCCH carrying the downlinkcontrol information is scrambled by a system information RNTI (SI-RNTI),to indicate receiving of the system information. Further, the formatindication information is used to indicate the type of the systeminformation.

Specifically, the format indication information may be indicationinformation that is in the downlink control information and that is usedto indicate a format. For example, a format of the downlink controlinformation may be a DCI format 0_0 or a DCI format 1_0, the downlinkcontrol information in the two formats includes a format indicationinformation bit, and the format indication information bit is used toindicate that the format of the downlink control information is the DCIformat 0_0 or the DCI format 1_0. The DCI format 0_0 is used to schedulesending of an uplink PUSCH, and the DCI format 1_0 is used to schedulereceiving of a downlink PDSCH.

In a specific implementation, different bit states or different bitvalues of the bits respectively indicate different system informationtypes. For example, the format indication information occupies one bit.Further, “0” is used to indicate the RMSI, “1” is used to indicate theOSI; or “1” is used to indicate the RMSI, and “0” is used to indicatethe OSI. For another example, the format indication information occupiesa plurality of bits. Further, “01” is used to indicate the RMSI, anotherstate is used to indicate the OSI, and the like.

It should be noted herein that the foregoing indication manner is merelyused as example for description, and a specific indication manner is notlimited herein.

Based on the foregoing description, it can be learned that a concept ofthe frequency domain reference point is introduced in NR, and afrequency domain reference point location needs to be considered duringdemodulation and receiving of the PDSCH, especially when differentsystem information types correspond to different frequency domainreference points. Based on Embodiment 1, this embodiment of theapplication provides Embodiment 2. Based on the foregoing optionaldesigns about configuration of the frequency domain reference point, asolution related to the frequency domain reference point is specificallyprovided. It should be noted herein that the solution in Embodiment 2 isbased on Embodiment 1, and may refer to some related content or allcontent in Embodiment 1. Details are not described herein again.

Based on some or all of the implementations in Embodiment 1, thefollowing several possible implementations are included in Embodiment 2.

In a possible implementation, different types of system informationcorrespond to a same frequency domain reference point. To be specific,the frequency domain reference point is a predefined or preconfiguredfrequency domain reference point, for example, a start resource block ofan initial active bandwidth part or a subcarrier numbered 0 in a startresource block of an initial active bandwidth part, for another example,a start resource block of a common index area or a subcarrier numbered 0in a start resource block of a common index area. In this possibleimplementation, a terminal device and a network device do not need toconsider a type of the system information, and perform PDSCHdemodulation and receiving based on a predefined or preset frequencydomain reference point.

In another possible implementation, different types of systeminformation correspond to different frequency domain reference points.The frequency domain reference point corresponds to the type of thesystem information, a correspondence exists between the type of thesystem information and the frequency domain reference point, and noadditional indication is required. FIG. 5 is used as an example, RMSIcorresponds to a frequency domain reference point A (namely, a startresource block of an initial active BWP or a subcarrier numbered 0 in astart resource block of an initial active bandwidth part), and OSIcorresponds to a frequency domain reference point B (namely, a startresource block of a common index area or a subcarrier numbered 0 in astart resource block of a common index area).

In this possible implementation, a location of a frequency domainreference point may be implicitly indicated by using the type of thesystem information, so that the type of the system information and thefrequency domain reference point may be indicated without additionalindication information, thereby improving communication efficiency andsimplifying a system design.

In this possible implementation, a predefined or configuredcorrespondence exists between the type of the system information and afrequency domain reference point location. For example, first-typesystem information corresponds to a first frequency domain referencepoint, and second-type system information corresponds to a secondfrequency domain reference point.

For example, a frequency domain reference point corresponding to theRMSI is the start resource block of the initial active BWP, and/or afrequency domain reference point corresponding to the OSI is the startresource block of the common index area.

Alternatively, a frequency domain reference point corresponding to theRMSI is the subcarrier numbered 0 in the start resource block of theinitial active BWP, and a frequency domain reference point correspondingto another system information type OS other than the RMSI is thesubcarrier numbered 0 in the start resource block of the common indexarea. The start resource block of the common index area is indicated byindication information carried in the RMSI.

In this implementation, for step 602, when determining, based on thetype of the system information, the frequency domain resource of thephysical downlink shared channel PDSCH carrying the system information,the network device needs to obtain a DMRS sequence based on the type ofthe system information. Different information types correspond todifferent DMRS sequences. For details, refer to the foregoingdescription.

Further, because different system information types correspond todifferent frequency domain reference points, the network devicedetermines a frequency domain location of the PDSCH. The network devicemodulates the DMRS sequence onto a physical resource, and sends thePDSCH carrying the system information.

For step 604, when the terminal device determines, based on theindication information, the frequency domain resource of the physicaldownlink shared channel PDSCH carrying the system information, theterminal device needs to obtain the frequency domain resource of thePDSCH based on the PDSCH frequency domain resource indicationinformation included in the DCI and the frequency domain reference pointcorresponding to the type of the system information. Further, beforedemodulating the PDSCH, the terminal device needs to obtain the DMRSsequence based on the type of the system information or the frequencydomain reference point, matches a received DMRS signal, and demodulatesand/or decodes the PDSCH.

In yet another possible implementation, another indication informationis used to indicate the frequency domain reference point correspondingto the system information.

In this possible implementation, the frequency domain reference point isseparately indicated, thereby improving flexibility of downlink resourcescheduling.

Optionally, different types of system information correspond todifferent frequency domain reference points, and the another indicationinformation indicates a frequency domain reference point correspondingto the type of the system information delivered by the network device.

Optionally, frequency domain reference points do not completelycorrespond to types of the system information, and the anotherindication information indicates a frequency domain reference pointcorresponding to the system information delivered by the network device.In this optional solution, for system information of a same type, thefrequency domain reference point may still be dynamically indicated byusing the indication information, thereby improving flexibility ofresource scheduling.

In an implementation, the another indication information may be an indexof a control resource set (CORESET) on which a PDCCH is located. Forexample, if the index of the CORESET is 0, the frequency domainreference point is a reference point A. If the index of the CORESET isnot 0, the frequency domain reference point is a reference point B.Specifically, the terminal device detects the PDCCH in a plurality ofCORESETs. If the PDCCH is detected in a CORESET 0, a frequency domainreference point for receiving the PDSCH is the reference point A. If thePDCCH is detected in another CORESET, the frequency domain referencepoint for receiving the PDSCH is the reference point B.

In another implementation, the another indication information may be oneof or a combination of the following included in the DCI: a hybridautomatic repeat request process number ((hybrid automatic repeatrequest, HARQ) process number), a new data indicator (New dataindicator. NDI), or a redundancy version (Redundancy version, RV).Specifically, the terminal device detects, based on an SI-RNTI, thePDCCH carrying the DCI, and determines, based on the one of or acombination of the HARQ process number, the NDI or the RV, that thefrequency domain reference point is the reference point A or B.

For example, if an information bit in the NDI is {0}, the frequencydomain reference point is the reference point A. If the information bitin the NDI is {1}, the frequency domain reference point is the referencepoint B.

In this possible implementation, for a specific interaction method,refer to the foregoing possible implementation. A difference between thetwo implementations lies only in different indication manners for thefrequency domain reference point. For a specific interaction manner inthis possible implementation, a person skilled in the art may performproper adjustment based on the foregoing possible implementation andaccording to different indication manners.

The solutions provided in the embodiments of the application are mainlydescribed above from a perspective of interaction between networkelements. It can be understood that, to implement the foregoingfunctions, the network elements such as the network device and theterminal device include corresponding hardware structures and/orsoftware modules for executing the functions. A person of ordinary skillin the art should easily be aware that, in combination with the exampleunits and algorithms steps described in the embodiments disclosed inthis specification, the application can be implemented by hardware or acombination of hardware and computer software. Whether a function isperformed by hardware or hardware driven by computer software depends onparticular applications and design constraints of the technicalsolutions. A person skilled in the art may use different methods toimplement the described functions for each particular application, butit should not be considered that the implementation goes beyond thescope of the application.

The following provides a further description based on a possiblestructure of the terminal device in FIG. 3. The terminal device canperform any method in the embodiments of the application. The terminaldevice may include at least the transceiver 301 and the processor 304(the processor is a general expression herein, and may represent a modemprocessor 304 or an integration of the modem processor 304 and theapplication processor 302). Optionally, the network device may furtherinclude other components in FIG. 3 and the description about FIG. 3,such as a memory. Herein, the transceiver 301 may include an independentreceiver and an independent transmitter, to separately performcorresponding receiving and sending functions; or may be a transceiverthat integrates the receiving and sending functions. No furtherlimitation is imposed herein. The transceiver 301 in FIG. 3 may bestructurally split into a receiver 301A and a transmitter 301B. Theterminal device is used only as an optional entity for an exampledescription herein. The following provides a description by using awireless apparatus as an entity. The wireless apparatus may be a unit, achip, or a component included in the terminal device, or may be theterminal device.

For Embodiment 1 and Embodiment 2 of the application:

The wireless apparatus includes a processor 304 and a receiver 301A,where

the processor 304 is configured to detect a physical downlink controlchannel PDCCH carrying downlink control information, the PDCCH carriesindication information, and the indication information is used toindicate a type of system information;

the processor 304 is configured to determine, based on the indicationinformation, a physical resource carrying the system information; and

the receiver 301A is configured to receive the system information on thephysical resource.

Specifically, a cyclic redundancy code CRC included in the PDCCH isscrambled by a radio network temporary identifier RNTI.

In an optional design, the indication information is a value of theRNTI, where the value of the RNTI is a first radio network temporaryidentifier RNTI, and the downlink control information is used toindicate first-type system information; and/or the value of the RNTI isa second radio network temporary identifier RNTI, and the downlinkcontrol information is used to indicate second-type system information.

In an optional design, the indication information is format indicationinformation, and the format indication information is carried in thedownlink control information.

In an optional design, the processor is configured to obtain, based on afrequency domain reference point, a demodulation reference signal DMRScorresponding to the physical resource carrying the system information;and the frequency domain reference point corresponds to the type of thesystem information.

Further, a correspondence between the frequency domain reference pointand the type of the system information is preconfigured or predefined.Alternatively, the frequency domain reference point is indicated byusing second indication information.

A time domain resource and/or frequency domain resource of the PDCCH isindicated by using information carried in a synchronization/broadcastchannel block.

It should be noted that, for a specific implementation of acommunication method performed by the wireless apparatus, refer to thedescription of the communication method provided in the embodiments ofthe application. The terminal device in this embodiment of theapplication and the communication method corresponding to FIG. 6 arebased on a same concept, and technical effects brought by the terminaldevice are the same as those of the communication method. Specificfunctions of the processor and the receiver included in the wirelessapparatus in this embodiment of the application and any features, terms,and implementation details that are related to the specific functionsare corresponding to the functions of the terminal device in the methodembodiment corresponding to FIG. 6. For specific content, refer to thedescription of the method embodiment corresponding to FIG. 6 in theapplication. Details are not described herein again.

It should be noted that, all or some of the foregoing embodiments may beimplemented by the wireless apparatus by using software, hardware,firmware, or any combination thereof.

For a structure of the wireless apparatus, in another optional manner,corresponding component in the foregoing embodiment may be implementedby corresponding hardware, or may be implemented by correspondinghardware by executing corresponding software. For example, the foregoingreceiver 301A may be hardware that has the foregoing receiving function,for example, a transceiver that integrates receiving and sendingfunctions or a receiver that only implements a receiving function, ormay be a general processor or another hardware device that can execute acorresponding computer program to implement the foregoing function, ormay be a software module or a functional unit that executes acorresponding function, for example, a receive unit. For anotherexample, the foregoing processor 304 may be hardware that has a functionof executing the processor, for example, a processor with a specificfunction, or a general processor, or may be another hardware device thatcan execute a corresponding computer program to complete the foregoingfunction, or may be a software module or a functional unit that executesa corresponding function, for example, a processing unit. For yetanother example, the transmitter 301B may be hardware that has theforegoing sending function, for example, a transceiver that integratesreceiving and sending functions, or a transmitter that only implements atransmit function, or may be a general processor or another hardwaredevice that can execute a corresponding computer program to implementthe foregoing function, or may be a software module or a functional unitthat executes a corresponding function, for example, a transmit unit.Optionally, the wireless apparatus may further include a storage unit.For details, refer to FIG. 7.

The following further describes a possible structure of the networkdevice in FIG. 2. The network device can perform any method in theembodiments of the application. The network device may include at leastthe controller or processor 201 (the processor 201 is used as an examplefor description in the following) and the transceiver 202. Optionally,the network device may further include other components in FIG. 2 and inthe description about FIG. 2, such as a memory. The transceiver 202herein may include an independent receiver and transmitter, andrespectively perform corresponding receiving and sending functions, ormay be a transceiver that integrates receiving and sending functions. Nofurther limitation is imposed herein. The transceiver 202 in FIG. 2 maybe structurally split into a receiver 202A and a transmitter 202B. Thenetwork device is used only as an optional entity for an exampledescription herein. The following provides a description by using awireless apparatus as an entity. The wireless apparatus may be a unit, achip, or a component included by the network device, or may be thenetwork device.

For Embodiment 1 and 2 of the application:

The wireless apparatus includes the processor 201 and the transmitter202B, where

the transmitter 202B is configured to send a physical downlink controlchannel PDCCH carrying downlink control information, the PDCCH carriesindication information, and the indication information is used toindicate a type of system information; and

the processor 201 is configured to determine, based on the type of thesystem information, a physical resource carrying the system information.

Specifically, the PDCCH includes a cyclic redundancy code CRC. Theprocessor is configured to scramble the CRC by using a radio networktemporary identifier RNTI.

In an optional design, the indication information is a value of theRNTI, where the value of the RNTI is a first radio network temporaryidentifier RNTI, and the downlink control information is used toindicate first-type system information; and/or the value of the RNTI isa second radio network temporary identifier RNTI, and the downlinkcontrol information is used to indicate second-type system information.

In an optional design, the indication information is format indicationinformation, and the format indication information is carried in thedownlink control information.

In an optional design, the transmitter 202B is configured to send ademodulation reference signal DMRS of the physical resource carrying thesystem information. The DMRS corresponds to a frequency domain referencepoint, and the frequency domain reference point corresponds to the typeof the system information.

In this optional design, a correspondence between the frequency domainreference point and the type of the system information is preconfiguredor predefined. Alternatively, the transmitter 202B is configured to sendsecond indication information, and the second indication information isused to indicate the frequency domain reference point corresponding tothe type of the system information.

A time domain resource and/or frequency domain resource of the PDCCH isindicated by using information carried in a synchronization/broadcastchannel block.

It should be noted that, for a specific implementation of acommunication method performed by the wireless apparatus, refer to thedescription of the communication method provided in the embodiments ofthe application. The network device in this embodiment of theapplication and the communication method corresponding to FIG. 6 arebased on a same concept, and technical effects brought by the networkdevice are the same as the foregoing control resource obtaining method.Specific functions of the processor and the receiver included in thewireless apparatus in this embodiment of the application and anyfeatures, terms, and implementation details that are related to thespecific functions are corresponding to the functions of the networkdevice in the method embodiment corresponding to FIG. 6. For specificcontent, refer to the description of the method embodiment correspondingto FIG. 6 in the application. Details are not described herein again.

It should be noted that, all or some of the foregoing embodiments may beimplemented by the wireless apparatus by using software, hardware,firmware, or any combination thereof.

For a structure of the wireless apparatus, in another optional manner,corresponding component in the foregoing embodiment may be implementedby corresponding hardware, or may be implemented by correspondinghardware by executing corresponding software. For example, the foregoingtransmitter 202B may be hardware that has the foregoing sendingfunction, for example, a transceiver that integrates receiving andsending functions or a transmitter that only implements a sendingfunction, or may be a general processor or another hardware device thatcan execute a corresponding computer program to implement the foregoingfunction, or may be further a software module or a functional unit thatexecutes a corresponding function, for example, a transmit unit. Foranother example, the foregoing processor 201 may be hardware that has afunction of executing the processor, for example, a processor with aspecific function, or a general processor, or may be another hardwaredevice that can execute a corresponding computer program to complete theforegoing function, or may be further a software module or a functionalunit that executes a corresponding function, for example, a processingunit. For another example, the receiver 202A may be hardware that hasthe foregoing sending function, for example, a transceiver thatintegrates receiving and sending functions, or a receiver that onlyimplements a receiving function, or may be a general processor oranother hardware device that can execute a corresponding computerprogram to implement the foregoing function, or may be further asoftware module or a functional unit that executes a correspondingfunction, for example, a receive unit. Optionally, the wirelessapparatus may further include a storage unit. For details, refer to FIG.7.

It can be understood that, the accompanying drawings show only asimplified design of the wireless apparatus. In an actual application,the wireless apparatus may include any quantities of transmitters,receivers, processors, controllers, memories, communications units, andthe like.

An embodiment of the application further provides a communicationssystem, including at least one network device and at least one terminaldevice described for executing the embodiments of the application.

An embodiment of the application further provides an apparatus (forexample, an integrated circuit, a wireless device, and a circuitmodule), configured to implement the foregoing communication method. Anapparatus for implementing a power tracker and/or a power generatordescribed in this specification may be a standalone device or may be apart of a larger device. The device may be: (i) an independent IC, (ii)a set of one or more ICs, where the set may include a memory IC forstoring data and/or instructions, (iii) an RFIC, such as an RF receiveror an RF transmitter/receiver, (iv) an ASIC, such as a mobile stationmodem, (v) a module that can be embedded in another device, (vi) areceiver, a cellular phone, a wireless device, or a mobile unit, or(vii) others.

The method and the apparatus provided in the embodiments of theapplication may be applied to a terminal device or a network device (maybe collectively referred to as a wireless device). The terminal deviceor the network device or the wireless device may include a hardwarelayer, an operating system layer running on the hardware layer, and anapplication layer running on the operating system layer. The hardwarelayer includes hardware such as a central processing unit (centralprocessing unit, CPU), a memory management unit (memory management unit,MMU), and a memory (also referred to as a main memory). The operatingsystem may be any one or more computer operating systems that implementservice processing by using a process (process), such as the Linuxoperating system, the UNIX operating system, the Android operatingsystem, the iOS operating system, or the Windows operating system. Theapplication layer includes applications such as a browser, an addressbook, word processing software, and instant messaging software. Inaddition, a specific structure of a method execution entity is notlimited in the embodiments of the application, provided that the methodexecution entity can perform communication based on the signaltransmission method in the embodiments of the application by running aprogram that records code of the method in the embodiments of theapplication. For example, the wireless communication method in theembodiments of the application may be performed by the terminal device,or the network device, or a function module that is in the terminaldevice or the network device and that can call and execute a program.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiments are merely examples. For example, the unit division ismerely logical function division. There may be another division mannerin actual implementation. For example, a plurality of units orcomponents may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual couplings or direct couplings or communicationconnections may be implemented by using some interfaces. The indirectcouplings or communication connections between the apparatuses or unitsmay be implemented in electronic, mechanical, or other forms.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions in the embodiments of theapplication, or the part contributing to the prior art, or some of thetechnical solutions may be implemented in the form of a softwareproduct. The computer software product is stored in a storage medium,and includes several instructions for instructing a computer device(which may be a personal computer, a server, a network device, or thelike) to perform all or some of steps of the method described in theembodiments of the application. The storage medium includes variousmedia that can store program code, such as a USB flash drive, aremovable hard disk, a read-only memory (ROM. Read-Only Memory), arandom access memory (RAM, Random Access Memory), a magnetic disk, or anoptical disc.

The descriptions are only specific implementations of the application,but are not intended to limit the protection scope of the application.Any variation or replacement readily figured out by a person skilled inthe art within the technical scope disclosed in the application shallfall within the protection scope of the application. Therefore, theprotection scope of the application shall be subject to the protectionscope of the claims.

What is claimed is:
 1. A method, comprising: obtaining, by a terminaldevice, downlink control information (DCI) by detecting a physicaldownlink control channel (PDCCH) carrying the DCI, wherein the downlinkcontrol information comprises indication information, and the indicationinformation indicates that a type of system information is either systeminformation type1 (SIB1) or a system information (SI) message other thanSIB1; determining, by the terminal device according to the indicationinformation, a physical resource carrying the system information;obtaining, by the terminal device according to a frequency domainreference point, a demodulation reference signal (DMRS) for the physicalresource, wherein the frequency domain reference point is one of atleast two frequency domain reference points, and the frequency domainreference points that are used to obtain DMRSs are different for theSIB1 and the SI message other than SIB1; and obtaining, by the terminaldevice based on the DMRS, the system information on the physicalresource.
 2. The method according to claim 1, wherein a cyclicredundancy code (CRC) comprised in the DCI is scrambled by a systeminformation-radio network temporary identifier (SI-RNTI).
 3. The methodaccording to claim 1, wherein the indication information is formatindication information.
 4. The method according to claim 1, wherein theindication information is an radio network temporary identifier (RNTI),wherein when the RNTI is a first RNTI, the downlink control informationindicates that the type of the system information is SIB1; or when theRNTI is a second RNTI, the downlink control information indicates thetype of the system information is SI message.
 5. The method according toclaim 1, wherein the indication information is one bit carried in theDCI.
 6. The method according to claim 5, wherein when the one bit is afirst value, the downlink control information indicates that the type ofthe system information is SIB1; or when the one bit is a second value,the downlink control information indicates the type of the systeminformation is SI message.
 7. The method according to claim 1, wherein apreconfigured or predefined correspondence exists between the at leasttwo frequency domain reference points and types of the systeminformation; or the frequency domain reference point is indicated bysecond indication information.
 8. The method according to claim 1,wherein at least one of a time domain resource and frequency domainresource of the PDCCH is indicated by information carried in asynchronization/broadcast channel block.
 9. An apparatus, comprising atleast one processor and a memory, where the memory stores a computerprogram, and when the processor executes the computer program, theapparatus is enabled to implement: obtaining downlink controlinformation (DCI) by detecting a physical downlink control channel(PDCCH) carrying the DCI wherein the downlink control informationcomprises indication information, and the indication informationindicates that a type of system information is either system informationtype1 (SIB1) or a system information (SI) message other than SIB1;determining, according to the indication information, a physicalresource carrying the system information; obtaining, according to afrequency domain reference point, a demodulation reference signal (DMRS)for the physical resource, wherein the frequency domain reference pointis one of at least two frequency domain reference points, and thefrequency domain reference points that are used to obtain DMRSs aredifferent for the SIB1 and the SI message other than SIB1; and obtainingbased on the DMRS, the system information on the physical resource. 10.The apparatus according to claim 9, wherein a cyclic redundancy code(CRC) comprised in the DCI is scrambled by a system information-radionetwork temporary identifier (SI-RNTI).
 11. The apparatus according toclaim 9, wherein the indication information is format indicationinformation.
 12. The apparatus according to claim 9, wherein theindication information is an radio network temporary identifier (RNTI),wherein when the RNTI is a first RNTI, the downlink control informationindicates that the type of the system information is SIB1; or when theRNTI is a second RNTI, the downlink control information indicates thetype of the system information is SI message.
 13. The apparatusaccording to claim 9, wherein the indication information is one bitcarried in the DCI.
 14. The apparatus according to claim 13, whereinwhen the one bit is a first value, the downlink control informationindicates that the type of the system information is SIB1; or when theone bit is a second value, the downlink control information indicatesthe type of the system information is SI message.
 15. The apparatusaccording to claim 9, wherein a preconfigured or predefinedcorrespondence exists between the at least two frequency domainreference points and types of the system information; or the frequencydomain reference point is indicated by second indication information.16. The apparatus according to claim 9, wherein at least one of a timedomain resource and frequency domain resource of the PDCCH is indicatedby information carried in a synchronization/broadcast channel block. 17.A non-transitory storage medium, configure to store programinstructions; wherein, when executed by a computer, the instructionscause the computer to perform: obtaining, downlink control information(DCI) by detecting, a physical downlink control channel (PDCCH) carryingthe DCI, wherein the downlink control information comprises indicationinformation, and the indication information indicates that a type ofsystem information is either system information type1 (SIB1) or a systeminformation (SI) message other than SIB1; determining, according to theindication information, a physical resource carrying the systeminformation; obtaining, according to a frequency domain reference point,a demodulation reference signal (DMRS) for the physical resource,wherein the frequency domain reference point is one of at least twofrequency domain reference points, and the frequency domain referencepoints that are used to obtain DMRSs are different for the SIB1 and theSI message other than SIB1; and obtaining, based on the DMRS, the systeminformation on the physical resource.
 18. The non-transitory storagemedium according to claim 17, wherein a cyclic redundancy code (CRC)comprised in the DCI is scrambled by a system information-radio networktemporary identifier (SI-RNTI).
 19. The non-transitory storage mediumaccording to claim 17, wherein the indication information is formatindication information.
 20. The non-transitory storage medium accordingto claim 17, wherein the indication information is an radio networktemporary identifier (RNTI), wherein when the RNTI is a first RNTI, thedownlink control information indicates that the type of the systeminformation is SIB1; or when the RNTI is a second RNTI, the downlinkcontrol information indicates the type of the system information is SImessage.
 21. The non-transitory storage medium according to claim 17,wherein the indication information is one bit carried in the DCI. 22.The non-transitory storage medium according to claim 21, wherein whenthe one bit is a first value, the downlink control information indicatesthat the type of the system information is SIB1; or when the one bit isa second value, the downlink control information indicates the type ofthe system information is SI message.
 23. The non-transitory storagemedium according to claim 17, wherein a preconfigured or predefinedcorrespondence exists between the at least two frequency domainreference points and types of the system information; or the frequencydomain reference point is indicated by second indication information.24. The non-transitory storage medium according to claim 17, wherein atleast one of a time domain resource and frequency domain resource of thePDCCH is indicated by information carried in a synchronization/broadcastchannel block.
 25. The method according to claim 1, wherein the physicalresource comprises at least one of a time domain resource of a physicaldownlink shared channel (PDSCH) and a frequency domain resource of thePDSCH.
 26. The apparatus according to claim 9, wherein the physicalresource comprises at least one of a time domain resource of a physicaldownlink shared channel (PDSCH) and a frequency domain resource of thePDSCH.
 27. The non-transitory storage medium according to claim 17,wherein the physical resource comprises at least one of a time domainresource of a physical downlink shared channel (PDSCH) and a frequencydomain resource of the PDSCH.